Bicyclic derivatives of hexahydroaporphine: novel agents that lower intraocular pressure.

We have synthesized a number of novel bicyclic hexahydroaporphines containing a phenethylamine moiety for preliminary study as intraocular pressure lowering agents. The target molecules were synthesized in a twelve step process. The final products were secondary or tertiary amines containing either an aromatic methoxy or phenolic substituent. These molecules, in hydrochloride salt form, were assayed in doses ranging from 0.1-1.5%. All products and vehicle were administered topically to one eye of normotensive rabbits and intraocular pressure was measured in both eyes for up to six hours. Four of the five compounds examined produced a significant and, in some cases, prolonged, ocular hypotensive response. Secondary and N-methylated tertiary amines were equally effective, as were compounds containing either the 10-methoxy group of free phenol. Studies are currently in progress to optimize potency and identify functional and molecular mechanisms of action.

Assessment of the in vivo and in vitro opioid activity of bridged hexahydroaporphine and isoquinoline molecules.

Four novel racemic bridged hexahydroaporphine (1 and 2) and isoquinoline (3 and 4) analogues have been synthesized in an attempt to generate bicyclic derivatives of the morphinan ring system. The opioid activity of these analogues has been assessed through membrane-binding studies, in vitro studies in isolated guinea pig ileum and mouse vas deferens, and in vivo studies utilizing the mouse hot plate technique. The bridged isoquinoline precursor molecules were inactive as antinociceptives. Both the racemic phenolic hexahydroaporphine 1 and its 10-methoxy congener 2 demonstrated dose-dependent, albeit weak, antinociceptive activity when administered icv, but they induced lethal convulsions when given subcutaneously. The antinociception elicited by 1 appeared to show very weak opioid character while that caused by 2 was totally nonopioid.

Effect of tamoxifen treatment on liver, lung and intestinal mixed-function oxidases in male and female rats.

Tamoxifen is a nonsteroidal antiestrogen which is used as an adjuvant form of chemotherapy for breast carcinomas containing estrogen receptors. Tamoxifen citrate (2 mg/rat/day) administration to male rats significantly decreased hepatic microsomal aryl hydrocarbon hydroxylase and 7-ethoxycoumarin O-de-ethylase activities and cytochrome P-450 content. These effects may be exerted through an antiandrogenic activity of tamoxifen, because plasma testosterone concentrations were also decreased. In male rats, tamoxifen treatment also depressed lung and intestinal microsomal aryl hydrocarbon hydroxylase and 7-ethoxycoumarin O-de-ethylase activities. Tamoxifen citrate treatment of female rats had no effect on hepatic, pulmonary, or intestinal microsomal aryl hydrocarbon hydroxylase or 7-ethoxycoumarin O-de-ethylase activities or hepatic cytochrome P-450 content. The results support the contention that estrogens at physiologic levels do not exert a significant regulatory effect on xenobiotic metabolism. Furthermore, androgens are known to influence drug metabolism, and the results indicate that tamoxifen has some antiandrogenic activity.

Effect of hypophysectomy and castration on hepatic, pulmonary and intestinal aryl hydrocarbon hydroxylase activities in the rat.

The importance of the pituitary gland in the regulation of hepatic drug and steroid metabolism has been previously demonstrated. The present studies involving castrated and hypophysectomized-castrated male rats confirm that the pituitary gland is essential for the expression of the effects of testosterone and dihydrotestosterone on hepatic aryl hydrocarbon hydroxylase (AHH) activity and cytochrome P-450 content. Furthermore, the pituitary gland is required for the inhibitor effects of estradiol on hepatic AHH activity in castrated male rats. Neither castration nor hypophysectomy-castration alters AHH activity in lungs or intestine. 2,3,7,8-Tetrachlorodibenzo-p-dioxin (TCDD) administration to control animals increased AHH activity by 2-, 15-, and 66.5-fold in liver, lungs and intestinal microsomes, respectively. Hypophysectomy did not prevent TCDD from acting as an inducer of AHH in any of the tissues, although the AHH activities in the three tissues were approximately 60% lower in TCDD-treated, hypophysectomized animals as compared to TCDD-treated, sham-operated control animals treated with TCDD. The results indicate that the pituitary gland plays an important role in regulating the extent of AHH induction in liver, lung and intestine.

Altered activities of hepatic and extrahepatic microsomal mixed function oxidase enzymes in diabetic and adrenalectomized diabetic rats.

Microsomal aryl hydrocarbon hydroxylase (AHH) and 7-ethoxycoumarin-O-deethylase (ECD) activities were determined in liver, lung and intestine of control, streptozotocin(STZ)-diabetic, and diabetic-adrenalectomized male and female rats. Hepatic cytochrome P-450 content was also determined. The diabetic state reduced hepatic AHH activity and increased ECD activity in control male rats, and failed to do so in the adrenalectomized male rats. The diabetic state increased hepatic AHH and ECD activities in the control female rats, while in the adrenalectomized female rats the activities of both enzymes were decreased compared to the control diabetic rats. STZ-induced diabetes produced a decrease in pulmonary AHH and ECD activities and increased intestinal AHH and ECD activities in both sexes. The diabetic state in the adrenalectomized rats resulted in further reduction in pulmonary AHH and ECD activities in both sexes, but failed to increase the intestinal AHH activity only in the female rat. Hepatic cytochrome P-450 contents were increased in the female but not male adrenalectomized rats when treated with STZ. The effects of STZ-induced diabetes in adrenalectomized rats on AHH, ECD and hepatic cytochrome P-450 content in liver, lung and intestine depended upon sex of animal, substrate and tissue.

Synthesis and biological activity of fluoroalkylamine derivatives of narcotic analgesics.

N-Ethyl-, N-(2-fluoroethyl)-, N-(2,2-difluoroethyl)-, and N-(2,2,2-trifluoroethyl)-substituted normeperidine (1b-e) and normetazocine (2b-e) derivatives were prepared. The analgesic activities of the compounds were determined in mice. Opiate receptor binding studies, in the presence and absence of sodium ion, were carried out. The antagonist activities of normetazocine derivatives were studied in monkeys. These were further examined in the isolated guinea pig ileum for relative agonist activity. The pKa values were measured; in vivo agonist acitivty was lost with weakly basic derivatives. For the normetazocine derivatives, opiate receptor binding data were consistent with guinea pig ileum agonist potency and mouse vas deferens antagonist potency but not with in vivo data. Opiate receptor binding was reduced for the less basic normetazocine derivatives. In the normeperidine series, there was no apparent direct relationship between pKa and opiate receptor binding. However, a relationship involving the hydrophobic character of the N-substituent is discussed. The N-(2-fluoroethyl) derivatives in both series were found to cause convulsions in rats at doses of 40-45 mg/kg ip. Elevated serum citrate levels were found in these rats, implicating in vivo oxidative deamination of the N-(fluoroalkyl) substituent to fluoroacetate.

Acetylcarnitine and cholinergic receptors.

Acetylcarnitine, a naturally occurring compound found in high concentration in heart and skeletal muscle of vertebrates, bears structural resemblance to acetylcholine, and studies have shown that it has slight cholinergic properties. Acetylcarnitine was subjected to conformational analysis by extended Hückel theory (EHT) and complete neglect of differential overlap (CNDO/2) molecular orbital methods. The preferred conformations were examined with respect to their similarity to the Kier and Chothia-Pauling models of cholinergic receptor patterns. The preferred conformations of both isomers did not fit the receptor pattern described by Kier's model, although energy barriers to rotation are low enough to permit accommodation. The Chothia-Pauling model predicts activity for the S-isomer only. These studies partially explain the low cholinergic activity found for acetylcarnitine and the higher activity of (S)-acetylcarnitine compared to the R-isomer.

Effect of gonadectomy on hepatic, lung and intestinal mixed function monooxygenase enzymes in the rat.

Aryl hydrocarbon hydroxylase (AHH) and 7-ethoxycoumarin O-deethylase (ECD) activities of microsomes from liver, lungs, and intestine of control and gonadectomized male and female rats were examined. Estradiol-treated ovariectomized female rats and testosterone-treated castrated male rats were also employed. Castration decreased hepatic AHH and ECD activities by 50% and 27%, respectively, whereas ovariectomy had no effect on these enzymes. Testosterone treatment of castrated male animals returned AHH and ECD activities to control values. Estradiol treatment of the ovariectomized female rats had no effect on the activities of these two enzymes. Gonadectomy of either sex did not alter AHH or ECD activities in microsomes from lungs and intestinal mucosa. No sex differences in lung AHH activities or lung and intestinal ECD activities were noted. AHH activities of liver and intestinal mucosa were greater by 86% and 42%, respectively, in male rats as compared to the female rats. Castration decreased the hepatic cytochrome P-450 content by 15%, while ovariectomy had no effect. The hepatic cytochrome P-450 content of control male rats was 27% higher than in the females. Organ specific alterations of mixed function monooxygenase enzymes occur with castration of male animals but not following ovariectomy of female rats.

Pharmacological assessment of 3-tert-butylsydnone.

The pharmacological effects of the mesoionic derivative, 3-tert-butylsydnone, were investigated. Administration to rats caused clonic convulsions. The CD50 of 3-tert-butylsydnone was 0.471 +/- 0.033 mmole/kg. Trimethadione, but not phenytoin sodium or proadifen hydrochloride, protected the rat from the effects of 3-tert-butylsydnone. After administration of this compound, pentobarbital sodium sleeping time was reduced in the rat, but blood pressure and ECG were unchanged in the dog. Pretreatment of the mouse with 3-tert-butylsydnone did not influence the LD50 of epinephrine hydrochloride. The action of methacholine chloride in the rat was not blocked, and the pupil of the rabbit eye was unaffected. Tests for analgesic and oxytocic activity were negative. Chronic administration of a small dose to the rat for 70 days had no effect on blood glucose, blood urea nitrogen, hemoglobin, or microhematocrit values.